The basic configuration of a typical representative video imaging apparatus 100 includes: an imaging unit 101 that images a video and generates imaging signals indicative of frame images of the video; an ISP (image signal processor) 102 that subjects the imaging signals to image signal processing to create the frame images of the video in sequence and, in the course of the creation, generates from the imaging signals imaging control values for controlling the imaging operation of the imaging unit 101, and performs a feedback control on the imaging operation of the imaging unit 101 according to the imaging control values; and a video output unit 103 that outputs the frame images of the video created by the ISP 102 in a video format capable of being reproduced on a monitor 105 as illustrated in FIG. 3. These components are arranged in a single imaging apparatus main body 104 (refer to JP-A-2015-161893).
The imaging control values generated by the ISP 102 from the imaging signals are auto white balance control values, auto exposure control values, or auto focus control values, or the like. The imaging operation of the imaging unit 101 is controlled by the imaging control values to subject the created frame images to auto white balance (AWB) by which to reproduce optimum colors under various different light sources, auto exposure (AE) by which to provide clear image quality according to brightness, and auto focus (AF) by which to obtain correct focus under various conditions. These imaging control values are acquired through comparison among all pixel data in the frame images indicated by the imaging signals. Accordingly, as the imaging element of the imaging unit 101 is higher in performance and the pixels of one frame image increase in number, the amount of data to be compared grows and leads to a rise in the costs of data mining processes such as filtering, scaling, and cropping for obtaining the imaging control values, and the load of processing from input of the imaging signals to the output of the frame images by the ISP 102 increases. Further, in the course of creating the frame images from the imaging signals, the ISP 102 is required to perform various signal processing operations such as noise reduction, shading correction, contour enhancement, and various effect functions. Therefore, the ISP 102 needs to include a microcomputer that consumes a large amount of power and has a complicated structure for high performance.
Meanwhile, in monitoring cameras mounted in medical endoscopes or vehicles, cameras for event data recorders, and others, the imaging unit needs to be arranged at a position distant from a monitor reproducing a video to image the video in a required imaging field of view. In a video imaging apparatus 110 described in JP-A-2015-136093, a camera module 113 including an imaging unit 112 is separated from an imaging apparatus main body 111, a complicated and large-sized ISP 115 with high power consumption is arranged on the imaging apparatus main body 111 side, and the camera module 113 and the imaging apparatus main body 111 are connected together via a LVDS (low voltage differential signaling) cable 114 as illustrated in FIG. 4.
According to the video imaging apparatus 110, the ISP 115 is not arranged in the camera module 113, and therefore the camera module 113 can be simplified and small-sized to operate with low power consumption.
The imaging signals output from the camera module 113 to the ISP 115 of the imaging apparatus main body 111 via the LVDS cable 114 are unprocessed imaging signals not yet subjected to the foregoing signal processing or de-mosaic processing for creating full-color images (hereinafter, called raw data). Accordingly, the data amount of the imaging signals is about ½ of that of the frame images output from the ISP 115 in YUV format, for example, and the time taken for transferring the imaging signals via the LVDS cable 114 at the same transfer speed is about ½ of that in the case where the ISP 115 is built in the camera module 113. Therefore, even when the LVDS cable 114 is laid in environments with frequent occurrence of noise, for example, in a vehicle, the capability of superimposition of noise on the transferred imaging signals reduces to about ½. Accordingly, the imaging signals are less influenced by influence of noise in unfavorable connection environments.